There has been very little systematic research attempting to isolate useful predictors of when acute low back pain incidents are likely to develop into chronic disability difficulties. With the great economic costs and traditionally poor outcomes among chronic low back pain disability patients, it becomes increasingly important to more effectively treat patients in the acute stage in order to avoid these more chronic problems. The major purpose of the present proposed prospective investigation is to evaluate whether DSM-III-R Axis I and II diagnoses, derived on the basis of a structured interview format (the Structured Clinical Interview for DSM-III-R -- SCID), will serve as useful predictors for those acute low back pain patients who subsequently develop chronic disability problems. This will provide the first important statistics on the incidence of specific psychiatric and personality disorders within an exclusively acute low back pain population that may be linked with subsequent chronicity. This more precise and standard classification of patients should significantly contribute to isolating important psychological and personality variables that may need to be treated, along with the acute pain episode itself, in order to prevent the development of a chronic low back pain syndrome. Three groups of subjects will be evaluated in the present study: (1) Acute low back pain patients (n = 1,000); (2) Non-pain medical patients with acute problems (n = 100); (3) Normal, pain-free and physically healthy subjects (n = 100). Besides comparing the incidence of DSM-III-R Axis I and II disorders in these groups, the major goal of this investigation will be to prospectively follow the acute low back pain patients over the next year in order to determine whether the presence of DSM-III-R disorders in the acute stage are predictive of the development of chronicity. Results will have a great many treatment and prevention implications for this costly and prevalent medical problem.